Heterotrophic fermentation of microorganisms is an efficient way of generating high value oil and biomass products. Under certain cultivation conditions, microorganisms synthesize intracellular oil, which can be extracted and used to produce fuel (e.g., biodiesel, bio-jetfuel, and the like) and nutritional lipids (e.g., polyunsaturated fatty acids such as DHA, EPA, and DPA). The biomass of some microorganisms is of great nutritional value due to high polyunsaturated fatty acid (PUFA) and protein content, and can be used as a nutritional supplement for animal feed. Thraustochytrids are eukaryotic, single-cell, microorganisms which can be used in such fermentation processes to produce lipids. Heterotrophic fermentations with Thraustochytrids convert organic carbon provided in the growth medium to lipids, which are harvested from the biomass at the end of the fermentation process. However, existing microorganism fermentations use mainly expensive carbohydrates, such as glucose, as the carbon source.